/* Copyright (C) 2000 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*
  Code for handling dubble-linked lists in C
*/

#include "mysys_priv.h"
#include <my_list.h>

/* Add a element to start of list */

LIST *list_add(LIST *root, LIST *element)
{
  DBUG_ENTER("list_add");
  DBUG_PRINT("enter", ("root: 0x%lx  element: 0x%lx", root, element));
  if (root)
  {
    if (root->prev) /* If add in mid of list */
      root->prev->next = element;
    element->prev = root->prev;
    root->prev = element;
  }
  else
    element->prev = 0;
  element->next = root;
  DBUG_RETURN(element); /* New root */
}

LIST *list_delete(LIST *root, LIST *element)
{
  if (element->prev)
    element->prev->next = element->next;
  else
    root = element->next;
  if (element->next)
    element->next->prev = element->prev;
  return root;
}

void list_free(LIST *root, uint free_data)
{
  LIST *next;
  while (root)
  {
    next = root->next;
    if (free_data)
      my_free((gptr)root->data, MYF(0));
    my_free((gptr)root, MYF(0));
    root = next;
  }
}

LIST *list_cons(void *data, LIST *list)
{
  LIST *new_charset = (LIST *)my_malloc(sizeof(LIST), MYF(MY_FAE));
  if (!new_charset)
    return 0;
  new_charset->data = data;
  return list_add(list, new_charset);
}

LIST *list_reverse(LIST *root)
{
  LIST *last;

  last = root;
  while (root)
  {
    last = root;
    root = root->next;
    last->next = last->prev;
    last->prev = root;
  }
  return last;
}

uint list_length(LIST *list)
{
  uint count;
  for (count = 0; list; list = list->next, count++)
    ;
  return count;
}

int list_walk(LIST *list, list_walk_action action, gptr argument)
{
  int error = 0;
  while (list)
  {
    if ((error = (*action)(list->data, argument)))
      return error;
    list = list_rest(list);
  }
  return 0;
}
